advice please help year 12 mocks (long read, but any help would be much appreciated!)

Hi, I don't have much knowledge about dentistry or the grades you need but from my personal experience of early entry, the college let me retake exams right after the summer holiday as there was still a month before the application deadline and I was able to improve my predicted grade based on those September exams (and work throughout the year) and still do early entry. It might be worth speaking to teachers about just doing the mocks after summer, hopefully they shouldn't say no as it is under your doctors advice

I got a pretty bad skin infection over a week ago now, due to my eczema, and im taking antibiotics for it. It's all over my face and my eyes and cheeks are swollen and itchy, red, rashy etc. Due to this I have not been able to revise much and pretty much wasted the first week of the half term break. Right after the break, I have year 12 mocks which determine my predicted grade which are sent off for ucas. As i am planning to do dentistry, i will have to apply for early entry, so these grades are final. I have spoken to my dermatologist, and she said i should not sit the exams, however if i do this i'm not sure what will happen about my predicted grades. I'm guessing that my school will most likely base it off my grades and work throughout the year, but i have mostly been getting C's, which will not be good enough if they base these for my predicted grades as i want to apply for dentistry. I am really stressed and worries on top of this skin infection which is taking a long time to go away, and now these mocks which determine my future. If someone could please give me some advice on what to do as i am very anxious about everything now. My plan for this break was to revise a lot for the whole two weeks as that should've been enough for the mocks. However I already know I will not be ready for the mocks if I go in like this, and will probs not get the grades I want which could ruin my ucas. I'm stuck someone please help. Should i start thinking about different careers? please help